From the southwest corner of the field at Mile High, where reporters congregate near the end of games, you could see Demaryius Thomas catch the ball in the distance and start rolling toward you.

You knew the play had started 80 yards from the goal line. You knew the Steelers had the No. 1-rated defense in the NFL. So you waited for someone in a white jersey to make the tackle.

And then he was turning upfield at the west sideline and coming right for you. Two defenders were charging toward the corner on steep angles. The closer they all got, the more obvious it became that Thom as was going to outrun them.

Overtime in the playoffs, even with the new rules, was going to consist of a single play. Was it even possible?

When Thomas crossed the goal line, the full house at Sports Authority Field exploded in paroxysms of joy, the Broncos’ stunning 29-23 overtime playoff victory over Pittsburgh in hand. In all these years of standing on football fields, I’ve never seen or heard or felt anything quite like it: Broncos players and staff grabbing one another and hugging like long-lost brothers. Champ Bailey walking around in a daze, as if he didn’t quite believe it. Players jumping into the stands. Face-painted fans screaming in ecstasy.

And Thomas unsure of what had just happened.

“To tell you the truth, I didn’t know why everybody was running over here, because I thought they got a chance to score,” Thom as said on the field a couple of minutes later. “But I seen everybody on the field, and I was like, ‘Oh, game over.’ I know the rules now.”

But how did it feel to be on the receiving end of a play that became instantly immortal?

“I feel amazing, man,” the young receiver said with a smile that seemed to stretch from sideline to sideline. “I feel amazing!”

It was not merely the culmination of a terrific performance from quarterback Tim Tebow, who saved his best for the biggest game of the season, against one of the toughest opponents.

It was not merely a story of redemption for the vastly talented Thomas, beset and beleaguered by injuries ever since Josh McDaniels made him and Tebow twin first-round draft picks 20 months ago.

It was also vindication of an inspired plan, the validation that only victory can provide for a coaching staff that lulled to sleep the best defense in football and then plunged home the dagger in the final scene.

Had the Broncos lost, you can bet the critics of coach John Fox and offensive coordinator Mike McCoy would have spent much of the offseason pointing out that of 23 first-down plays in regulation, the Broncos ran the ball 22 times. True, they passed twice on first downs that were nullified by penalties, but the pattern was more than clear:

The Broncos, as everyone had alleged, were soporifically predictable on first down. They were putting Tebow, their young quarterback, in the unenviable position of passing only when it was necessary, when the defense knew it was coming.

And here they were with a first down at their 20-yard line to begin overtime, and was there any doubt, any doubt at all, what they would do?

“I was all upset from the fumble I did,” said running back Willis McGahee, who seemed certain to get the ball. “If I wouldn’t have fumbled, we probably wouldn’t have been in that situation.

“It was play action. I was in there and did a good fake. The linebackers ran up and came into the line. (Steelers safety) Troy Polamalu came into the line too, so our job was done. But we still needed to execute the play, and we did that.”

“It’s a great call, first of all,” Tebow said. “Just off some of our zone-read stuff, (they were) bringing the safeties. … It was a great call by coach McCoy.”

“We called underneath coverage,” said Ryan Mundy, the Steelers’ other safety, who played in place of Ryan Clark, whose health prevents him from playing at high altitude. “I was underneath; (cornerback) Ike (Taylor) was over top.”

Actually, no, he wasn’t. Nobody was over the top. Nobody was guarding against the Broncos’ biggest play of the 21st century to date because nobody expected it. Everybody knows the Broncos never pass on first down.

When the last player had disappeared into the tunnel beneath the south stands, the delirious fans in the front rows, the fans painted orange, still stood there, looking at one another, as if to confirm they had seen what they had just seen, that it had actually happened, that they had just witnessed something so unbelievable they could not have imagined it.

KANSAS CITY, Mo. — Tyreek Hill didn’t know what to do when he started hearing thousands of people in Arrowhead Stadium chanting his name, even as he stood all alone on the frozen turf waiting for the punt.